<template>
  <div class="slider" ref="slider">
    <div class="slider-group" ref="sliderGroup" >
      <slot>
      </slot>
    </div>
    <div class="dots">
      <span class="dot" v-for="(item,index,key) in dots" :class="{active:currentPageIndex===index}" :key="key"></span>
    </div>
  </div>
</template>

<script>
import { addClass } from "common/js/dom";
import BScroll from "better-scroll";
export default {
  name: "slider",
  data(){
    return {
      dots:[],
      currentPageIndex:0
    }
  },
  props: {
    loop: {
      type: Boolean,
      default: true
    },
    autoPlay: {
      type: Boolean,
      default: true
    },
    interval: {
      type: Number,
      default: 3000
    }
  },
   activated() {
      if (this.autoPlay) {
        this._play()
      }
    },
  mounted() {
    setTimeout(() => {
      this._setSliderWidth();
      this._initDots();
      this._initSlider();
      if (this.autoPlay) {
          this._play()
        }
    }, 20);
    window.addEventListener('resize',()=>{
      if(!this.slider){
        return
      }
      this._setSliderWidth(true);
      // this.slider.refresh()
    })
  },
  methods: {
    _setSliderWidth(isResize) {
      this.children = this.$refs.sliderGroup.children;
      let width = 0;
      let sliderWidth = this.$refs.slider.clientWidth;
      for (let i = 0; i < this.children.length; i++) {
        let child = this.children[i];
        addClass(child, "slider-item");
        child.style.width = sliderWidth + "px";
        width += sliderWidth;
      }

      if (this.loop && !isResize) {
        width += 2 * sliderWidth;
      }

      this.$refs.sliderGroup.style.width = width + "px";
    },
    _initSlider() {
      console.log(this.$refs.slider);
      this.slider = new BScroll(this.$refs.slider, {
        scrollX: true,
        scrollY: false,
        momentum: false,
        autoPlay:this.autoPlay,
        snap: {
            loop: this.loop,
            threshold: 0.3,
            speed: 400
          },
        click:true
      });

      this.slider.on('scrollEnd',()=>{
        let pageIndex = this.slider.getCurrentPage().pageX;
        this.currentPageIndex=pageIndex;        
        if(this.autoPlay){
          clearTimeout(this.timer);
          this._play();
        }
      })
    },
    _initDots(){
      console.log(this.children.length);
      this.dots=new Array(this.children.length);
    },
    _play(){
      let pageIndex=this.currentPageIndex +1;
      this.timer=setTimeout(()=>{
        this.slider.next()
      },this.interval)
    }
  },
  destroyed(){
    clearTimeout(this.timer);
  }
};
</script>

<style lang="scss" scoped="" type="text/css">
.slider {
  position: relative;
  .slider-group {
    /* display: flex; */
    overflow: hidden;
    position: relative;
    .slider-item {
      float: left;
      box-sizing: border-box;
      overflow: hidden;
      text-align: center;
      img {
        display: block;
        width: 100%;
        height: 100%;
      }
    }
  }
  .dots{
      position: absolute;
      right: 0;
      left: 0;
      bottom: 12px;
      text-align: center;
      font-size: 0;
      .dot{
        display: inline-block;
        margin: 0 4px;
        width: 8px;
        height: 8px;
        border-radius: 50%;
        background:#ffffff;
        &.active{
          width: 20px;
          border-radius: 5px;
          background: #ffffff;}
   }
  }
}
</style>
